Tec

hn

isc

he

Un

ive

rsit

t

M

nc

he

nW

ind

En

erg

yIn

sti

tute

Aeroelasticity- Introduction

Carlo L. Bottasso, Stefano Cacciola

October 2014

Aero

ela

sti

cit

y:

Intr

oducti

on

-2-

What is Aeroelasticity?

Definitions:

Aeroelasticity is the branch of physics and engineering that studies the interactions between [sic] the inertial, elastic, and aerodynamic forces that occur when an elastic body is exposed to a fluid flow. (Wikipedia, 2014)

The branch of applied mechanics which deals with the interaction of aerodynamic, inertial, and structural forces. (McGraw-Hill Science & Technology Encyclopedia, 2014)

The science of the interaction between aerodynamic forces and non-rigidstructures. (Oxford Dictionaries, 2014)

Best: Phenomena which exhibit appreciable reciprocal interaction (static or dynamic) between aerodynamic forces and the deformations induced thereby in the structure of a flying vehicle, its control mechanisms, or its propulsionsystem. (RL Bisplinghoff, H Ashley, Principles of Aeroelasticity, Dover Phoenix Editions, 2002)

Aero

ela

sti

cit

y:

Intr

oducti

on

-3-

What is Aeroelasticity?

Engineering and natural systems (vehicles, bridges and buildings, wires, wind turbines, plants, birds, ) are made up by forces, interacting within themselvesand with the external environment.

Bisplinghoff & Ashley, Principles of Aeroelasticity

Mutual interaction

Unidirectional interaction

Aero

ela

sti

cit

y:

Intr

oducti

on

-4-

What is Aeroelasticity?

Focus on specific appreciable reciprocal interactions:

Electromagnetic field Hydrodynamic forces

Thermodynamics

Controls

Aero[]elasticity

Aeroservothermoelasticity

Elastic forces Inertial forces Aerodynamic forces

Aeroservoelasticity

Aeroelasticity

Aero

ela

sti

cit

y:

Intr

oducti

on

-6-

What is Aeroelasticity?

Collars Triangle:

Aero

ela

sti

cit

y:

Intr

oducti

on

-7-

Why Does Aeroelasticity Matter?

Aeroelasticity is a crucial element of the design of many engineering systems

It is necessary to account for aeroelasticity within design to ensure:

Performance

Safety

http://youtu.be/OhwLojNerMU (old movies, but still completely relevant)

Aero

ela

sti

cit

y:

Intr

oducti

on

-8-

Why Does Aeroelasticity Matter?

Rotary wing aeroelasticity

Pogo instabilities in liquid fuel rocket engines

https://youtu.be/ykhbTfa449I

http://youtu.be/q9ocI0_SxrM

Pogo on Apollo 8 & 9

Aero

ela

sti

cit

y:

Intr

oducti

on

-9-

Why Does Aeroelasticity Matter?It matters not only for aerospace applications:

Galloping power lines

Aeroelasticity of civil structures

http://youtu.be/C2ZOlbxG9bc

http://youtu.be/0NmRF84lv1Y

Aero

ela

sti

cit

y:

Intr

oducti

on

-10-

Why Does Aeroelasticity Matter?It matters not only for aerospace applications:

Vibrations in pipes,

naval hydrodynamics,

tank sloshing,

biological flows,

musical instruments,

Possible energy harvesting concept

Aero-hydro-servo-elasticity of wind turbines

http://youtu.be/8mquJDJOqiU

http://youtu.be/DfGxsCQmye0

Aero

ela

sti

cit

y:

Intr

oducti

on

-11-

Why Does Aeroelasticity Matter?

Aeroelasticity in nature:

Morphing wings

Load-mitigating self-protecting structures

Cardiovascular flow, biological flows

http://youtu.be/Ni_mS4cKPXY

http://youtu.be/JA0Wb3gc4mE

http://youtu.be/siHQgN6iFRk